The present invention is directed to the field of railroad beds. More particularly, the present invention is directed to a railroad tie made of recycled tire treads having adequate compressive strength and torsional stiffness to withstand the loading associated with continuous rail transit.
There are a number of problems associated with conventional wooden rail ties. Continuous rail traffic and weathering causes splitting, allowing spikes to backout, which compromises the integrity of the rail bed. In addition, the creosote with which the wooden ties are treated constitutes an environmental hazard and its use has fallen into disfavor. The discarded ties themselves, once they have been removed from the rail bed, become a form of environmental waste littering the country side or providing a problem for land fills.
Another environmental disposal problem is associated with used automotive tires. Tires cannot be burned due to the resulting air pollution and they are not readily buried in land fills since the minimal bio-degradation which takes place can threaten to pollute surrounding water supplies. Accordingly, tire disposal has become a major environmental problem and most tire retailers impose a tire disposal fee with each tire replaced. It is the intention of the present invention to remedy these two environmental problems by turning the tire disposal problem into a resource material for producing railroad ties which do not require the application of creosote.
Several attempts have been made to manufacture a suitable rail tie from used automotive tires. For example, U.S. Pat. Nos. 6,824,070; 6,708,896; and 6,372,069 teach rail ties utilizing recycled tire treads. In addition, U.S. Pat. No. 5,996,901 has rigid plates laminated to the top and bottom of the stack of tires. However, none of these attempts have succeeded in providing a rail tie which has adequate compressive strength, torsional and bending stiffness to stand up under the rigors imposed by continuous rail traffic.
The present invention overcomes the problems with previous attempts by providing adequate compressive strength, as well as torsional and bending stiffness to withstand the continuous loading of rail traffic without degradation of the tie body or experiencing backout of the retention spikes.
The railroad tie of the present invention comprises an elongated tie which includes a) at least one stack of laminated tire treads forming a body of the tie; b) reinforcing means integrated into the at least one stack of laminated tire treads, the reinforcing means having a first portion providing increased compressive strength and a second portion providing increased torsional and bending stiffness to the elongated tie. More preferably, the at least one stack of laminated tire treads comprises at least two stacks of laminated tire treads, the reinforcing means including a vertical member that extends between the at least two stacks, and most preferably, the reinforcing means comprises an I-beam which has a stack secured into each recess between the flanges.
The reinforcing member is made of a material selected from a group consisting of wood, conductive metals, non-conductive metals and composites. It is preferable that the vertical member extends between the at least two stacks in non-contacting relationship to provide electrical isolation. This can be done by forming a gap which is filled with a non-conducting material. It is also preferred that a distal end of the vertical member be spaced from a lowermost element, the lowermost element forming a bottom surface of the elongated tie. In the preferred embodiment, an additional tire tread ply sandwiches each of the two reinforcing flanges of the I-beam between itself and at least one of the stacks of laminated tire treads.
It has proven advantages for a distal end of each flange of the I-beam to have a transverse flange extending parallel to said vertical member. In an alternative embodiment, the horizontal members of the I-beam are formed as upper and lower box flanges which are each filled with tire treads. Each flange of the I-beam has a group of cut-out portions to accommodate rail securing spikes. In one embodiment the I-beam has a hollow box spine. In yet another embodiment, at least one horizontally extending flange of the reinforcing member is corrugated. In certain embodiments, the laminated stacks of tire treads are made from recycled steel belted tires. In those embodiments, it is particularly important that the tire treads have periodic gaps formed in a length of each laminate layer to ensure electrical isolation between the two supporting rails. This permits signaling/monitoring electrical systems to be installed in the railroad ties of the present invention.
Various other features, characteristics and advantages of the present invention will become apparent after a reading of the following detailed description of the present invention.